import java.util.HashMap;
import java.util.Map;

public class Main {

	public static void main(String[] args) {
		
		Map<Object, Object> map = new HashMap<>();
		Student s = new Student("李四");
		Student s2 = new Student("李四");
		Student s3 = new Student("李四");
		map.put(s, "1");
		map.put(s2, "2");
		map.put(s3, "3");
		System.out.println(map.get(s2));
	}
}
